Hot start open nozzle fuel injection systems

Abstract

A fuel leakage prevention system for preventing undesired leakage of fuel into the combustion chambers of an internal combustion engine equipped with a pressure/time, cam actuated unit fuel injection system. The system includes a main housing containing an evacuatable chamber adapted to be connected by a first fluid conduit to a source of sub-atmospheric pressure by a check valve and manual shut off valve. The evacuatable chamber is also adapted to be fluidically connected to a common rail supplying fuel to the injectors by a solenoid controlled valve which is open during engine shutdown and closed during engine operation whereby fuel is withdrawn from the injectors by the vacuum upon engine shutdown.

I claim: 
     
       1. A fuel leakage prevention system for eliminating undesired leakage of fuel into the combustion chambers of a multi-cylinder internal combustion engine from a plurality of corresponding fuel injectors supplied with fuel by a common rail connected to the fuel injectors, comprising a main housing containing an evacuatable chamber;   vacuum forming means fluidically connected with said evacuatable chamber and adapted to be fluidically connected with a source of sub-atmospheric pressure during engine operation;   vacuum applying means connected with said evacuatable chamber and adapted to be fluidically connected with the common rail, said vacuum applying means including a first valve means for fluidically connecting said evacuatable chamber to the common rail when operating in a first mode in response to a control signal and for fluidically isolating the common rail from said evacuatable chamber when operating in a second mode in response to a control signal; and   control means for supplying said control signal to said first valve means to cause said first valve means to operate in said first mode during engine shut-down and to cause said first valve means to operate in said second mode during engine operation.   
     
     
       2. A fuel leakage prevention system as defined in claim 1, further including second valve means operatively connected with said vacuum forming means for isolating said evacuatable chamber from the source of sub-atmospheric pressure during engine shut-down. 
     
     
       3. A fuel leakage prevention system as defined in claim 2 for use with a fuel injection system including a fuel pump for supplying fuel at a controlled pressure to the common rail while creating a source of sub-atmospheric pressure, wherein said vacuum forming means includes a first fluid conduit fluidically connected at one end to said evacuatable chamber and adapted to be fluidically connected at the other end to the sub-atmospheric pressure forming portion of said fuel pump. 
     
     
       4. A fuel leakage prevention system as defined in claim 3, wherein said vacuum applying means including a second fluid conduit fluidically connected at one end to said evacuatable chamber and adapted to be fluidically connected at the other end to the common rail. 
     
     
       5. A fuel leakage prevention system as defined in claim 4, further including mounting hardware means for retrofitting the system on an existing internal combustion engine subject to performance problems associated with undesired fuel leakage into the combustion chambers. 
     
     
       6. A fuel leakage prevention system as defined in claim 5, further including adaptor fittings for connecting said first and second fluid conduits to the sub-atmospheric fluid pressure portion of the fuel pump and the common rail, respectively. 
     
     
       7. A fuel leakage prevention system as defined in claim 6, further including instructions for retrofitting the system to preexisting internal combustion engines and packaging for combining said instructions with the remaining elements of the system for shipment to retrofitting installers. 
     
     
       8. A fuel leakage prevention system as defined in claim 5 for use with an engine having an intake manifold with a preexisting array of bolt holes, wherein said hardware means includes a mounting bracket having a first array of mounting holes corresponding to the preexisting array of intake manifold bolt holes. 
     
     
       9. A fuel leakage prevention system as defined in claim 8, wherein said mounting bracket includes a second array of holes for receiving fasteners for mounting said main housing on said bracket and wherein said first and second arrays are offset and each said array is internally symmetrical to allow said bracket to be mounted on the engine intake manifold in one of two reversed positions to allow said main housing to be mounted in one of two offset positions using the said bracket. 
     
     
       10. A fuel leakage prevention system as defined in claim 2, wherein said second valve means includes a check valve for responding to pressure differences within said evacuatable chamber and the sub-atmospheric source to disconnect fluidically said evacuatable chamber from the sub-atmospheric source when the pressure within said evacuatable chamber falls below the pressure of the sub-atmospheric source. 
     
     
       11. A fuel leakage prevention system as defined by claim 1, wherein said first valve means includes a solenoid operator for converting said first valve means from said first mode to said second mode in response to electrical energization and spring bias means for returning said valve means to said second mode in response to loss of electrical energization. 
     
     
       12. A fuel leakage prevention system as defined by claim 1, wherein said main housing includes a vacuum port fluidically connected with the source of sub-atmospheric pressure and wherein said vacuum forming means includes a shutoff valve means for shutting off the fluid connection between said evacuatable chamber and the source of sub-atmospheric pressure, said shutoff valve means including a shutoff valve housing adapted to be mounted on said main housing in one of plural rotationally displaced positions about the central axis of said vacuum port, said shutoff valve housing including an internal passage connected at one end with said vacuum port and connected with a side port located radially from the rotational axis of said shutoff valve housing. 
     
     
       13. A fuel leakage prevention system as defined by claim 10, wherein said vacuum forming means includes a first conduit connected at one end to said side port and adapted to be connected at the other end to the source of sub-atmospheric pressure, whereby the directional orientation of said first conduit relative to said main housing may be changed by changing the rotational position in which said shutoff housing is mounted on said main housing. 
     
     
       14. A fuel leakage prevention system as defined by claim 12, wherein said shutoff valve means includes a manual operator for permitting manual shutoff of the fluid connection between said evacuatable chamber and the source of sub-atmospheric pressure. 
     
     
       15. A fuel injection system for injecting fuel periodically into the combustion chambers of a multi-cylinder internal combustion engine, comprising fuel pump means for forming a source of fuel under pressure;   a common rail for supplying fuel under pressure from said fuel pump means to each of the engine cylinders during engine operation;   a plurality of fuel injectors connected with said common rail for injecting fuel from said common rail into corresponding cylinders of the engine, each said fuel injector including an injection orifice from which fuel enters into the corresponding engine cylinder from said fuel injector on a periodic basis during engine operation, at least one of the engine combustion cylinders remaining fluidically connected with said common rail during engine shut down through a corresponding open injection orifice; and   vacuum applying means for preventing migration of fuel into the engine cylinders through said injection orifices during engine shut down by reducing the fluidic pressure within said common rail sufficiently to prevent fuel from migrating through said open injection orifices.   
     
     
       16. A fuel injection system as defined in claim 15, further including a main housing containing an evacuatable chamber; and vacuum forming means fluidically connected with said evacuatable chamber and adapted to be fluidically connected with a source of sub-atmospheric pressure during engine operation; and wherein said vacuum applying means is connected with said evacuatable chamber and adapted to be fluidically connected with said common rail, said vacuum applying means including a first valve means for fluidically connecting said evacuatable chamber to the common rail when operating in a first mode in response to a control signal and for fluidically isolating the common rail from said evacuatable chamber when operating in a second mode in response to a control signal; and further including control means for supplying said control signal to said first valve means to cause said first valve means to operate in said first mode during engine shut-down and to cause said first valve means to operate in said second mode during engine operation. 
     
     
       17. A fuel injection system as defined in claim 16, further including second valve means operatively connected with said vacuum forming means for isolating said evacuatable chamber from the source of sub-atmospheric pressure during engine shut-down. 
     
     
       18. A fuel injection system as defined in claim 17, wherein said fuel pump means creates a source of sub-atmospheric pressure, and wherein said vacuum forming means includes a first fluid conduit fluidically connected at one end to said evacuatable chamber and adapted to be fluidically connected at the other end to the sub-atmospheric pressure created by said fuel pump means. 
     
     
       19. A fuel injection system as defined in claim 18, wherein said vacuum applying means including a second fluid conduit fluidically connected at one end to said evacuatable chamber and adapted to be fluidically connected at the other end to the common rail. 
     
     
       20. A fuel injection system as defined in claim 17, wherein said second valve means includes a check valve for responding to pressure differences within said evacuatable chamber and the sub-atmospheric source to disconnect fluidically said evacuatable chamber from the sub-atmospheric source when the pressure within said evacuatable chamber falls below the pressure of the sub-atmospheric source. 
     
     
       21. A fuel injection system as defined by claim 16, wherein said first valve means includes a solenoid operator for converting said first valve means from said second mode to said first mode in response to electrical energization and spring bias means for returning said valve means to said second mode in response to loss of electrical energization. 
     
     
       22. A fuel injection system as defined by claim 16, wherein said main housing includes a vacuum port fluidically connected with the source of sub-atmospheric pressure and wherein said vacuum forming means includes a shutoff valve means for shutting off the fluid connection between said evacuatable chamber and the source of sub-atmospheric pressure, said shutoff valve means including a shutoff valve housing adapted to be mounted on said main housing in one of plural rotationally displaced positions about the central axis of said vacuum port, said shutoff valve housing including an internal passage connected at one end with said vacuum port and connected with a side port located radially from the rotational axis of said shutoff valve housing. 
     
     
       23. A fuel injection system for injecting fuel periodically into a combustion chamber of an internal combustion engine, comprising fuel injector having a body containing at least one injection orifice and an injection chamber into which fuel may be metered and from which the metered fuel may be expelled for periodic injection into the combustion chamber of the internal combustion engine through said injection orifice;   vacuum forming means for forming a sub-atmospheric pressure; and   vacuum applying means for preventing migration of the supplied fuel from said injection chamber into the combustion chamber during shut down of the internal combustion engine by fluidically connecting said vacuum forming means with said injection chamber during engine shut-down.   
     
     
       24. A fuel injection system as defined in claim 23, wherein said body contains a central bore and wherein said injector includes a cam operated, injector plunger mounted for reciprocating movement within said central bore to form said injection chamber, said injection orifice being positioned adjacent one end of said central bore such that said injection orifice remains open to said corresponding injection chamber when said injector plunger is displaced from said one end of said central bore. 
     
     
       25. A fuel injection system as defined in claim 24, further including a common rail for supplying fuel to said fuel injector, said injector plunger causing said injection chamber to be fluidically connected with said injection orifice and the corresponding combustion chamber whenever said injector plunger is retracted at least a predetermined distance from said open injection orifice. 
     
     
       26. A fuel injection system as defined in claim 25, further including a main housing containing an evacuatable chamber; and vacuum forming means fluidically connected with said evacuatable chamber and adapted to be fluidically connected with a source of sub-atmospheric pressure during engine operation; and   wherein said vacuum applying means connected with said evacuatable chamber and fluidically connected with said common rail, said vacuum applying means including a first valve means for fluidically connecting said evacuatable chamber to the common rail when operating in a first mode in response to a control signal and for fluidically isolating the common rail from said evacuatable chamber when operating in a second mode in response to a control signal; and   control means for supplying said control signal to said first valve means to cause said first valve means to operate in said first mode during engine shut-down and to cause said first valve means to operate in said second mode during engine operation.   
     
     
       27. A fuel injection system as defined in claim 26, further including second valve means operatively connected with said vacuum forming means for isolating said evacuatable chamber from the source of sub-atmospheric pressure during engine shut-down. 
     
     
       28. A fuel injection system as defined in claim 27, further including a fuel pump for supplying fuel at a controlled pressure to said common rail while creating a source of sub-atmospheric pressure, wherein said vacuum forming means includes a first fluid conduit fluidically connected at one end to said evacuatable housing and fluidically connected at the other end to the sub-atmospheric pressure within the fuel injection system. 
     
     
       29. A fuel injection system as defined in claim 28, wherein said vacuum applying means includes a second fluid conduit fluidically connected at one end to said evacuatable chamber and adapted to be fluidically at the other end to the common rail.